ES2813613T3 - Hot melt adhesive composition based on a blend of propylene copolymers prepared using catalysts and single site processes - Google Patents

Abstract

A hot melt adhesive composition comprising: (a) a polymer blend containing at least one semi-crystalline LMW SSC-PP polymer and at least one essentially amorphous HMW SSC-PP copolymer; which are homopolypropylene or copolymers of propylene with an α-olefin comonomer prepared using SSC catalysts; the weight ratio of the LMW SSC-PP polymer to the HMW SSC-PP polymer in the blends ranges from 9: 1 to 1: 9 and the total amount of the polymer blend in the composition of the present invention is 20% 80% by weight; with LMW SSC-PP having a density of 0.86 g / cc at 0.90 g / cc at 23 ° C, a weight average molecular weight of 10,000 g / mol at 100,000 g / mol, a melting point of 20 ° C to 140 ° C, a melting enthalpy of 30 J / g to 100 J / g, a crystallinity of 18% to 50%, a melt flow rate equal to or greater than 80 g / 10 min, and a Brookfield viscosity at 190 ° C, which ranges preferably from 800 mPa.s to 100,000 mPa.s; and the HMW PP polymer having a density of 0.85 g / cc to 0.88 g / cc at 23 ° C, a weight average molecular weight greater than 100,000 g / mol, with no melting point or a residual melt from 20 ° C to 120 ° C, a melting enthalpy of 0 J / g to 30 J / g, a crystallinity of 0% to 18% and a melt flow rate (FMR) equal to or less than 200 g / 10 minutes; (b) a compatible tackifier in the amount of 15% by weight to 75% by weight; (c) from 1% to 35% by weight of a plasticizer; (d) 0.1% to 3% by weight of a stabilizer or antioxidant; and (e) optionally from 0% to 20% by weight of a wax.

Description

DESCRIPTION

Hot melt adhesive composition based on a blend of propylene copolymers prepared using catalysts and single site processes

Field of the invention

This invention relates to a new polymer blend based hot melt adhesive composition comprising polypropylene polymers prepared using single site catalysts. More particularly, the polypropylene polymer blend comprises a low molecular weight semi-crystalline propylene polymer and a high molecular weight essentially amorphous propylene polymer, thus producing a polymer component having a bimodal molecular weight distribution. The adhesive composition has well balanced adhesion and cohesion properties and is useful in packaging, product assembly, and laminations. The adhesive composition is particularly useful for bonding low surface energy substrates often seen in the manufacture of a variety of disposable nonwoven sanitary products, such as baby diapers, adult incontinence supplies, and feminine hygiene pads.

Background of the invention

Hot melt adhesives typically exist as a solid mass at room temperature and can be converted to a flowable liquid through the application of heat. These adhesives are particularly useful in the manufacture of a variety of disposable products where the bonding of various substrates is often necessary. Specific applications include disposable diapers, hospital pads, feminine sanitary napkins, protective pads, surgical drapes, and adult incontinence briefs, collectively known as disposable nonwoven sanitary products. Other diversified applications have involved paper products, packaging materials, automotive coatings, appliances, tapes, and labels. In most of these applications, the hot melt adhesive is heated to its molten state and then applied to a substrate, often referred to as a primary substrate. A second substrate, often referred to as a secondary substrate, is immediately contacted and compressed against the first. The adhesive solidifies on cooling to form a strong bond. The main advantage of hot melt adhesives is the absence of a liquid vehicle, as would be the case with water- or solvent-based adhesives, thus eliminating the costly process associated with solvent removal.

For many applications, hot melt adhesives are often extruded directly onto a substrate in the form of a thin film or a bead using gear or piston pump equipment.

In this case, the substrate is brought into intimate contact with a hot matrix under pressure. The temperature of the die must be kept well above the melting point of the adhesive to allow the molten hot melt material to flow smoothly through the application nozzle. For most applications, particularly those found in food packaging and nonwoven disposable sanitary ware manufacturing, bonding of delicate and heat sensitive substrates such as thin gauge plastic films is often involved. This imposes an upper limit on the coating temperature for hot melt applications. Current commercial hot melts are typically formulated to have a coating temperature below 200 ° C, preferably below 150 ° C, to avoid burning or distortion of the substrate. In addition to direct coating, various indirect or non-contact coating methods are also developed, through which a hot melt adhesive can be sprayed with the help of compressed air onto a remote substrate. These non-contact coating techniques include conventional spiral spray, Omega ™, Surewrap ™, and various forms of melt blowing processes. However, the indirect process requires that the viscosity of the adhesives be low enough, generally in the range of 2,000 to 30,000 mPa.s, preferably in the range of 2,000 to 15,000 mPa.s, at the application temperature to obtain a pattern. acceptable coating. Many other physical factors, especially the rheological properties of the adhesive, come into play in determining the sprayability of a hot melt. Most commercial hot melt products do not lend themselves to spray applications. There are no accepted theoretical models or guidelines for predicting sprayability, which must be determined empirically with the application equipment.

Hot melt adhesives are organic materials that typically consist of a polymer, a plasticizer, a tackifying resin, and an antioxidant package. Other ingredients such as wax, fillers, colorant, and UV absorber, can also be used to modify adhesive properties or to provide special attributes. These organic ingredients are prone to thermal degradation under adhesive coating conditions. For example, the widely used commercial hotmelt adhesive based on styrene-isoprene-styrene triblock copolymer (SIS), when subjected to 175 ° C for 24 hours, can suffer a viscosity drop of approximately 50 percent of its value. original. Styrene-butadiene-styrene (SBS) hot melt can cause crosslinking problems under similar conditions. Crosslinking can result in a dramatic increase in viscosity and can eventually cause the adhesive to not flow through the formation of a three-dimensional polymer network. The change in viscosity is often accompanied by charring, gelling, and skinning on top of the molten material. Degradation will inevitably lead to deterioration of the properties and performance of the adhesive. In addition, they can also cause equipment damage. The rate of degradation depends on temperature; the higher the temperature, the faster the degradation. Therefore, reducing the coating temperature of the adhesive can slow down degradation.

Conventional polyolefins produced using Ziegler-Natta (ZN) catalysts such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), and isototatic polypropylene (iPP) do not lend themselves to adhesive applications. Ziegler-Natta (ZN) catalyst systems consist of a catalyst and cocatalyst pair. The most common of these pairs are TiCta and Al (C2H5) 2Cl, or TiCl4 with Al (C2H5) 3. Ziegler-Natta catalyst systems are the subject of numerous publications in scientific journals and textbooks and are well known to those of skill in the art. A conventional ZN catalyst system is typically integrated into an inert support and has several catalyst sites, each of which has a different activity. This difference in activity causes the formation of polymer molecules with a plurality of molecular weights and composition of copolymer molecules. Polyolefin homopolymers and copolymers produced with ZN catalysts are typically high crystallinity and rigid. This can result in a hot melt adhesive that is relatively brittle or has poor substrate wetting, poor adhesion, and poor processability. However, hot melt adhesives containing various types of polyolefin blends are known from various previous patent publications.

As used herein, Z-N refers to a Ziegler-Natta catalyst for olefin polymerization.

As used herein, LDPE and HPDE refer to low-density polyethylene and high-density polyethylene, respectively.

As used herein, iPP refers to isotactic propylene homopolymers or copolymers that predominantly have an isotactic chain structure.

As used herein, amorphous poly-alpha-olefin (APAO) refers to a class of homopolymers or copolymers of low molecular weight amorphous propylene with ethylene or butene typically produced with a Lewis acid catalyst.

As used herein, "PB" refers to polybutene homopolymers and copolymers.

For example, Trotter et al, in US Patent No. 4,022,728, describe a hot melt pressure sensitive composition comprising a blend of APAO, a low molecular weight substantially amorphous elastomer, a liquid tackifier and a conventional crystalline polypropylene (iPP) in the amount of up to 2% by weight. According to the '728 patent, the composition provides good adhesive properties at low temperatures.

Meyer et al, in US Patent 4,120,916, describe hot melt adhesive compositions comprising a blend of low molecular weight PE, low molecular weight iPP, and APAO. These adhesive compositions are said to offer short open times and are useful for bonding paraffin modified corrugated board.

Lakshmanan et al., In US Patent No. 4,761,450, describe a polymer blend useful as a hot melt adhesive comprising an LDPE, a copolymer of butene-1 with ethylene or propylene, a hydrocarbon tackifier and a low molecular weight polymer consisting of a low molecular weight liquid polybutene, an APAO, and mixtures thereof.

Ryan describes in US Patent No. 5,747,573 an APAO-based hot melt adhesive composition useful for bonding plastics and foil containers. The adhesive composition contains a mixture of APAO, a solid benzoate plasticizer, and a hydrocarbon tackifier.

United States Application No. 2014/0358100 A1 relates particularly to a disposable absorbent article comprising: a first substrate and a second substrate; and an adhesive composition applied to at least one of the first or second substrates, said adhesive composition comprises: a first polymer that is based on propylene and has a Mw no greater than about 75,000, a second polymer that is based on propylene and has a Mw of at least about 100,000, wherein the propylene-based polymers have a polydispersity index of less than about 5, and wherein the adhesive composition is used in at least two different applications in the disposable absorbent article.

The combination of APAO with polyethylene (PE), polybutene copolymers (PB) or conventional iPP leads to serious drawbacks. Prior art adhesives containing APAO / PE or APAO / PB blends, such as, for example, those previously described in US Patents 4,120,916 and 4,761,450 tend to have poor compatibility. These adhesives can undergo phase separation during the application process when the hot melt adhesive must be held in a molten state at a high temperature for an extended period of time, sometimes for hours or even days. Charring, peeling, and gelling can develop fairly quickly in phase-separated hot melt adhesives, causing application equipment to become blocked or plugged. The incompatibility of such polymer blends also facilitates brittleness, optical haze, poor or no open time, and low bond strength. Although conventional APAO and iPP blend-based hot melts do not have the compatibility issues, they can still suffer from all the others. drawbacks described above in the present document. Furthermore, due to the high crystallinity and high melting point of conventional iPP polymers, hot melt adhesives based on APAO / iPP blends tend to be hard and brittle unless the amount of iPP polymer is kept at a very low level. , such as about or below 2% by weight as described in US Patent 4,022,728. As a result, these adhesives will have poor tensile strength, poor bond strength, and poor impact resistance. Another detrimental effect of iPP is the increase in temperature of the coating. The adhesive must be heated well above the melting point of iPP (between 180 and 200 ° C) to reach the liquid state. Although the combination of the atactic high and low molecular weight polyolefin approach described in US Patent 5,723,546 offers some improvement in the tensile properties of APAO, it has not been able to provide sufficient tensile strength and properties. high temperature to overcome the shortcomings of APAO-based hot melts.

The deficiencies in the prior art mentioned above are partially overcome by the more recent inventions described in US Patent 6,329,468, which teaches the use of flexible semi-crystalline polyolefin for hot melt adhesive compositions; in US Patent 7,262,251 which teaches a hot melt adhesive composition based on a random copolymer (RCP) of isotactic polypropylene and a secondary polymer; in US patent application publication US2003 / 0096896 A1 which describes a hot melt composition comprising a mixture of syndiotactic polypropylene (sPP) and APAO; in US Patent 8,383,731 which describes an adhesive blend based on a semi-crystalline copolymer of propylene with an alpha-olefin. However, all these compositions consist of a rigid semi-crystalline polymer that is not uniform in the intramolecular and / or intermolecular composition distribution, and in the tacticity distribution of the molecular chains. It is not the intention of the present invention to dwell on theoretical discussions of the property-function relationships of the polymer, but the lack of uniformity in the composition and structure of the chain, together with a very wide distribution of molecular weight, may be responsible. poor adhesive properties and poor processability for a hot melt composition. These semi-crystalline polymers in the above compositions can have a rigid polymer chain structure, which is detrimental to the adhesion and application properties of hot melt adhesives containing such polymers. It is extremely difficult, if not impossible, to balance the complex requirements of adhesion, cohesion, low viscosity, wide application temperature range, and applicability through a wide range of application procedures.

More recently, Tse et al in US patent 9,109,143 disclosed an adhesive composition containing a blend of two low molecular weight propylene-based copolymers having a weight average molecular weight (Mw) of less than 100,000 g / mol. The low molecular weight propylene copolymers of the '143 patent also have low melting point and low crystallinity. Copolymers, primarily aimed at sealing corrugated boxes, have poor cohesive strength and therefore do not lend themselves to a variety of demanding applications such as elastic fastening for non-woven hygiene products and liner assembly. automatic roof.

US Patent Application No. 2016/0121014 describes a disposable absorbent article and adhesive composition that includes a first polymer that is based on propylene and has a molecular weight of no more than about 75,000 and a second polymer selected from a group including propylene-based polymers with a molecular weight of at least about 100,000 and styrene block copolymers with a styrene content of not more than about 20%, where the adhesive composition is claimed to be useful for elastic bonding applications.

Summary of the invention

Therefore, it would be advantageous to provide a hot melt adhesive that overcomes the deficiencies of the prior art adhesives mentioned above. It is found in the present invention that a polyolefin polymer blend comprising a low molecular weight semi-crystalline polymer, polypropylene based single site catalyst (SSC-PP from LMW) and a high molecular weight essentially amorphous polymer, catalyst of Polypropylene based single site (HMW SSC-PP) provides a unique combination of properties that prior art hot melt systems have failed to offer, thus providing high bond strength to a variety of low surface energy substrates such as films made of LDPE and iPP, high cohesive strength to keep elastic materials under constant tension, excellent thermal stability, good wetting property, wide application temperature range, long open time, good green bond strength and suitability for essentially all known hot melt coating processes.

In accordance with the present invention, a hot melt adhesive composition is composed of a blend of propylene polymers produced using single site catalysts (SSC); a high molecular weight essentially amorphous polypropylene polymer (HMW's SSC-PP polymer) and a low molecular weight semi-crystalline polypropylene copolymer (LMW's SSC-PP polymer). The different molecular weights of the component polymers result in a polymer blend having a bimodal molecular weight distribution. In addition to the difference in molecular weights, the SSC-PP polymer in the blend also differs in the enthalpy of fusion, which is an indirect measure of the crystallinity of the polymer. For the purposes of the present invention, LMW semi-crystalline SSC-PP polymer is defined as homo- or copolymers of propylene having a weight average molecular weight (Mw) of 100,000 g / mol or less, a different melting point in the DSC curve, and a melting enthalpy per above 30 joules per gram of material (J / g). HMW's essentially amorphous SSC-PP polymer is defined as homo- or copolymers of propylene having a weight average molecular weight (Mw) greater than 100,000 g / mol, and containing no or essentially no crystalline phase at all or a small residual crystallinity fraction characterized by a small but notable melting point on a differential scanning calorimetry (DSC) curve with a melting enthalpy below 30 joules per gram of material (J / g). HMW's essentially amorphous SSC-PP polymer can also be completely amorphous without showing a melting peak on its DSC curve. The composition also includes a tackifier component, a plasticizer component, an antioxidant package, and optionally other additives such as a wax, filler, colorant, UV absorber, and other polymer. The composition is suitable for applications with a variety of direct and indirect coating procedures and has a novel combination of properties including low coating temperature, wide coating temperature range, excellent adhesion to low surface energy plastic substrates, high cohesive strength , high shear strength, good yarn retention property, low viscosity, low melting point and superior thermal stability. The composition of the present invention is particularly useful for food packaging, product assembly, and disposable nonwoven assembly for bonding polyethylene and polypropylene films, nonwovens, and elastic yarns to each other or to themselves.

As used herein, "SSC" refers to single site catalysts for α-olefin polymerization.

As used herein, Mw refers to the weight average molecular weight of a polymer.

For the purposes of the present invention, the term "essentially amorphous" is used to refer to a state in which a PP-based polymer exhibits an enthalpy of fusion from 0 J / g to about 30 J / g.

For the purposes of the present invention, the term semi-crystalline is used to refer to a state in which a PP-based polymer exhibits an enthalpy of fusion above 30 J / g.

As used herein, HMW SSC-PP refers to a class of high molecular weight essentially amorphous propylene homopolymers or copolymers produced using single site catalysts having a Mw greater than about 100,000 g / mol. . Polymers can be completely amorphous without showing melting peaks on a DSC curve, but they can also have a small fraction of crystals that give rise to a small but noticeable melting peak on a DSC curve, or peaks with associated melting enthalpy of 30 joules per gram of material (J / g), or less, that is, from 0 J / g to about 30 J / g.

As used herein, the DSC curve refers to a graph of heat flux or heat capacity versus temperature obtained using a differential scanning calorimetry (DSC) instrument. The test procedure used to determine these values is ASTM E793-01 “Standard Test Method for Enthalpies of Fusion and Crystallization by Differential Scanning Calorimetry”.

As used herein, LMW SSC-PP refers to a class of low molecular weight semi-crystalline propylene homopolymers or copolymers having a weight average molecular weight (Mw) of about 100,000 g / mol or less, and a distinct melting peak or peaks on a DSC curve with associated enthalpy of melting of 30 joules per gram of material (J / g) or greater, i.e., typically from about 30 J / g to about 100 J / g, more preferably from about 30 J / g to about 90 J / g, and most preferably about 35 J / g to about 80 J / g. The terms "enthalpy of fusion", "enthalpy of fusion", "heat of fusion" and "heat of fusion" are used interchangeably.

As used herein, SSC-PP blend refers to a polymer blend comprising at least one HMW SSC-PP polymer and at least one LMW SSC-PP polymer.

Therefore, the present invention is directed to hot melt adhesive compositions comprising a polypropylene polymer blend containing a semi-crystalline LMW SSC-PP polymer and an essentially amorphous HMW SSC-PP polymer with a material to material ratio of LMW. HMW ranging from 9: 1 to 1: 9 parts by weight. The adhesive composition comprises, in addition to the SSC-PP mixture, a tackifying resin, a plasticizer and an antioxidant system as main ingredients. The compositions of the present invention have taken advantage of the complementary properties between the semi-crystalline LMW SSC-PP polymer and the essentially amorphous HMW SSC-PP polymer and have overcome the deficiencies of prior art polyolefin-based hot melt adhesives. Compositions according to the embodiments of the present invention provide well balanced tensile strength, toughness, flexibility and adhesion properties. They exhibit high bond strength to a variety of low surface energy substrates such as LDPE and iPP films, high cohesive strength to keep elastic materials under constant stress, excellent thermal stability, good wetting properties, wide application temperature range , long open time, good green bond strength, low viscosity, low or no residual tack when set, and suitability with essentially all known hot melt coating processes. In particular, the embodiments of the present invention lead to an adhesive composition that is well suited for a variety of spray coating application techniques, such as, for example, spiral spray, Omega ™, Surewrap ™, blown. fusion, Control Coat® and the like, and sprayless coating application techniques such as, for example, slot coating, V-slot ™, Allegro ™ and the like; these techniques of Coating are well known to those skilled in the art and are not a subject of discussion of the present invention.

Therefore, an object of the present invention is to provide a hot melt adhesive composition comprising a polymer blend containing at least one semi-crystalline LMW SSC-PP polymer and at least one essentially amorphous HMW SSC-PP polymer; both are homopolymers of propylene or copolymers of propylene with an alpha-olefin comonomer prepared using single site catalysts (SSC) and have a statistically random comonomer distribution along the polymer chain. The weight ratios of the semi-crystalline LMW SSC-PP polymer to the essentially amorphous HMW SSC-PP polymer in the blends range from 9: 1 to 1: 9 and the total amount of the polymer blend in the composition herein The invention is 20% to 80% by weight, preferably 30% to 60% by weight, and most preferably 30% to 50% by weight.

The semi-crystalline LMW SSC-PP polymer may be present in embodiments of the invention in an amount of between 5% to 50% by weight, more preferably between 10% to 35%, and most preferably between 15% to 30%. . The essentially amorphous HMW SSC-PP polymer may be present in embodiments of the invention in an amount of between 7% to 35% by weight, more preferably between 10% to 30%, and most preferably between 15% to 28%. %. When various ranges of any constituent are provided herein, the invention contemplates that the composition may contain a range of that constituent that extends from a lower limit of a first range to an upper limit of a second range, for example, the Semi-crystalline LMW SSC-PP polymer is present in an amount ranging from 5% to 30%. Furthermore, as for these two specific constituents, the composition of the invention may contain a reported range of the semi-crystalline LMW SSC-PP with any of the reported ranges of the essentially amorphous HMW SSC-PP polymer, for example, 5% to 50%. % by weight of the semi-crystalline LMW SSC-PP polymer and 15% to 28% of the essentially amorphous HMW SSC-PP polymer.

Additionally, preferred embodiments of the composition of the present invention comprise an essentially amorphous HMW SSC-PP polymer in an amount of 15% to 28%, more preferably 18% to 28%, even more preferably 20% to 28%, even more preferably 22% to 28%, and alternatively, at least 23%, 24%, or 25% up to 50%, 45%, 35%, or any of the upper limits described herein. According to such embodiments, the composition of the present invention comprises the semi-crystalline LMW SSC-PP polymer in an amount of 5% to 50% by weight, more preferably between 10% to 35%, and most preferably between 15%. % to 30%, and alternatively, between 5% and 20%.

A second objective of the present invention is to teach the technique of formulating a hot melt adhesive composition containing the aforementioned polymer blend in combination with a plasticizer, a compatible tackifier and antioxidant. The composition may contain optional additives including, but not limited to, a wax, a functionalized polymer, a colorant, a UV absorber, and a filler.

A third objective of the present invention relates to a hot melt composition comprising the polymer mixture having a low viscosity ranging from 500 mPa.s to 35,000 mPa.s at 177 ° C, preferably from 1000 mPa.s to 20,000 mPa.s and so on. more preferably 2,000 mPa.s to 15,000 mPa.s. Low viscosity is essential for applications involving various spray coating procedures.

Another object of the present invention is to provide a hot melt adhesive composition for nonwoven elastic bonding applications having a creep retention of at least 80% or more; a value of 80% (based on the methodology described herein) is generally the minimum acceptable to the disposable nonwoven sanitary articles industry.

The present invention encompasses any application that involves the bonding of similar or different substrates using a hot melt adhesive at a temperature lower than 200 ° C, preferably equal to or lower than 160 ° C while obtaining a good cohesion of the adhesive bond to resist mechanical stress at low, ambient or elevated temperatures, particularly under creep conditions. The present composition is particularly advantageous for bonding printed or coated cardboard that has the low surface energy of plastic materials, such as paper boxes for freezing food packaging, where the boxes are often coated with a barrier material against moisture to protect its contents from drying during storage, or printed for aesthetic reasons, or both. For such packaging applications, the present composition allows resistance to fiber breakage in coated and printed boxes at low temperatures below freezing, where conventional ethylene vinyl acetate (EVA) hot melts do not work. Therefore, another object of the present invention is to provide a hot melt for low temperature packaging applications.

Another object of the present invention is to teach a process for preparing the hot melt adhesive composition that involves a batch process.

Another object of the present invention is to provide a hot melt adhesive composition having good low temperature processability, below 160 ° C, for applications involving heat sensitive substrates that are inevitably found in the manufacture of absorbent nonwoven hygiene articles, where Fine gauge LDPE films and PP non-woven fabrics are typically used.

Another objective is to teach the technique of applying the hot melt composition of the present invention through the use of various hot melt coating procedures and to provide a method for joining or laminating two or more substrates by first applying the hot melt to the primary substrate and subsequently pairing the primary substrate. to a secondary substrate.

A further objective of the present invention is to provide a hot melt adhesive composition that is particularly useful for various applications in the manufacture of absorbent nonwoven sanitary articles including, but not limited to, baby diapers, sweat pants, incontinence articles adults, feminine pads, protective pads, surgical gowns and absorbent pads for poultry meat, the composition exhibiting well balanced properties of tensile strength, toughness, flexibility and adhesion. Exhibits high bond strength to a variety of low surface energy substrates, such as LDPE and iPP films, high cohesive strength for holding elastic materials, such as elastic yarns, under constant tension, excellent thermal stability, good wetting property, broad application temperature range, long open time, good green bond strength, low viscosity, low or no residual tack when set, and adequacy with essentially all known hot melt coating processes.

Also described is a hot melt adhesive composition comprising as components thereof a mixture of the following ingredients:

to. a polymer blend comprising at least one semi-crystalline LMW SSC-PP polymer and at least one essentially amorphous HMW SSC-PP polymer; which are homopolypropylene or copolymers of propylene with an α-olefin comonomer prepared using SSC catalysts and have a statistically random comonomer distribution along the polymer chain. The weight ratios of the semi-crystalline LMW SSC-PP polymer to the essentially amorphous HMW SSC-PP polymer in the blends range from 9: 1 to 1: 9 and the total amount of the polymer blend in the composition herein invention is from about 20% to about 80% by weight, preferably from about 30% to about 60% by weight, and most preferably from about 30% to about 50% by weight; LMW's SSC-PP polymer has a density of about 0.86 g / cc to about 0.90 g / cc at 23 ° C, a weight average molecular weight of about 10,000 g / mole to about 100,000 g / mole, a melting point of approximately 20 ° C to approximately 150 ° C, an enthalpy of fusion of approximately 30 J / g to approximately 100 J / g, a crystallinity of approximately 18% to approximately 55% and a melt viscosity of approximately 800 mPa .s to about 100,000 mPa.s; and HMW PP copolymer has a density of about 0.85 g / cc to about 0.88 g / cc at 23 ° C, a weight average molecular weight greater than 100,000 g / mol, with no melting point or a melting from about 20 ° C to about 120 ° C, a melting enthalpy of about 0 J / g to about 30 J / g, a crystallinity of about 0% to about 18% and a melt flow rate (FMR) equal to or less than 200 g / 10 min according to ASTM D-1238 at 230 ° C / 2.16 kg of test conditions;

b. a compatible tackifier in the amount of about 15% by weight to about 75% by weight, preferably in the amount of about 30% by weight to about 60% by weight;

c. from about 1% to about 35% by weight, preferably from about 2% to about 20% by weight, of a plasticizer;

d. from about 0.1% to about 3% by weight, preferably from about 0.2% to about 1.0% by weight, of a stabilizer or antioxidant; Y

and. optionally from about 0% to about 20% by weight, preferably from about 0% to about 15% by weight, of a wax.

The components of the composition (which may include more additional components) totaling 100% by weight. The adhesive composition may contain other components such as a filler and / or a colorant and / or a fluorescent agent and / or another polymer that can modify the adhesive properties of the above basic adhesive composition.

Also described is a hot melt adhesive composition comprising as components thereof a mixture of the following ingredients:

to. a polymer blend containing at least one semi-crystalline LMW SSC-PP polymer and at least one essentially amorphous HMW SSC-PP copolymer; which are homopolypropylene or copolymers of propylene with an α-olefin comonomer prepared using SSC catalysts; the weight ratio of the LMW SSC-PP polymer to the HMW SSC-PP polymer in the blends ranges from 9: 1 to 1: 9 and the total amount of the polymer blend in the composition of the present invention is about 20 % to about 80% by weight, preferably from about 30% to about 60% by weight and most preferably from about 30% to about 50% by weight; LMW SSC-PP has a weight average molecular weight of about 10,000 g / mol to about 100,000 g / mol, a crystallinity of about 18% to about 50%, and a Brookfield viscosity at 190 ° C which preferably ranges from about 800 mPa.s to about 100,000 mPa.s; and the HWM SSC-PP polymer with a weight average molecular weight greater than 100,000 g / mol, and a crystallinity of about 0% to about 18%, wherein the molecular weight of the HMW PP polymer is at least twice that of SSC-PP molecular weight of LMW;

b. a compatible tackifier in the amount of about 15% by weight to about 75% by weight, preferably in the amount of about 30% by weight to about 60% by weight;

c. from about 1% to about 35% by weight, preferably from about 2% to about 20% by weight, of a plasticizer;

d. from about 0.1% to about 3% by weight, preferably from about 0.2% to about 1.0% by weight, of a stabilizer or antioxidant;

and. optionally from about 0% to about 20% by weight, preferably from about 0% to about 15% by weight, of a wax.

Detailed description of the invention

According to the present invention, a hot melt adhesive composition is produced, which comprises as base polymer components a mixture of a semi-crystalline LMW SSC-PP polymer and an essentially amorphous HMW SSC-PP polymer; both polymers prepared using single-site catalyst systems, which can be distinguished from conventional ZN catalyst systems in several ways. Ziegler-Natta catalyst systems generally consist of a catalyst and cocatalyst pair and the most common of these pairs is TiCl3 and Al (C ² Hs) ² Cl, or TiCl4 with Al (C2Hs) 3. Conventional ZN catalyst systems are typically integrated into an inert support and have several active catalyst sites on a support particle, each of which has a different activity. In the homopolymerization of α-olefins, the more active sites incorporate more monomer molecules into the backbone of the polymer, thus producing polymer molecules that have relatively longer chain lengths or higher molecular weight. In contrast, less active sites will give rise to shorter chain polymer molecules. Polymers produced by the ZN catalyst will have a very broad molecular weight distribution with a polydispersity index (PDI) of up to 10, while polymers made by SSC catalysts have a narrow molecular weight distribution with a PDI typically of about 2 to approximately 4. The PDI is defined as the ratio of weight average molecular weight (Mw) / number average molecular weight (Mn). With ZN catalysts, the polymerization reaction is highly stereospecific. The α-olefin molecules add to the polymer chain only in a particular orientation, depending on the chemical and crystalline structure of the catalyst, thus producing a regular repeating three-dimensional polymer chain configuration. In the scientific nomenclature of polymers, the term tacticity is used to describe the chain configuration, that is, the stereo structure of a polymer chain. A polymer is called isotactic if it has a described chain configuration that has the radical groups attached to the tertiary carbon atoms of successive monomer units on the same side of a hypothetical plane drawn through the main chain of the polymer. This type of stereochemical structure can be graphically illustrated using Fisher's projection formula as follows:

Polypropylene that has this type of chain configuration is known as isotactic polypropylene or iPP.

A polypropylene chain can also adopt a syndiotactic configuration in which the tertiary methyl groups of successive monomer units along the chain are arranged alternately on each side of the hypothetical plane. The stereo configuration of the syndiotactic chain can be represented below:

Polypropylene that has this type of chain configuration is called syndiotactic polypropylene, or sPP.

In contrast to a regular spatial configuration, a propylene polymer chain can also have a chain stereo structure characterized by having the methyl groups in successive monomer units sterically randomly distributed on both sides of the hypothetical plane through the polymer chain. This string configuration is defined as atactic. The stereo configuration of the atactic polypropylene (aPP) molecular chain can be graphically illustrated using the following Fisher projection formula:

The commercial Z-N catalysts in use today are designed to produce a predominantly isotactic chain configuration. However, this stereoselectivity is not entirely sufficient and a monomer insertion error can occur, characterized by the occasional addition of a syndiotactic carbon atom along the predominantly isotactic polymer chain. The error in selectivity results in local random configurations and the interruption of the regularity of the chain, thus producing some atactic fraction. This phenomenon explains a small but significant amorphous fraction in iPP polymers. The different active sites on a supported Z-N catalyst mentioned above also exhibit different stereoselectivity, some of the sites being more faithful in producing isotactic configuration than the others. The resulting polypropylene inevitably consists of a complicated heterogeneous series of molecules having different chain lengths and tacticity. Despite the difference in the individual molecules, the stereo configuration of polypropylene is, however, predominantly isotactic. Due to this structure, polypropylenes are macroscopically a semi-crystalline material that has a high degree of crystallinity and a high melting point.

The molecular structures of propylene copolymers with other α-olefins produced by Z-N catalysts are even more complex. In addition to the differences in molecular weights and tacticity mentioned herein, copolymer molecules also have differences in composition in terms of comonomer content due to differences in activities at the active sites of the catalyst towards comonomers. This leads to heterogeneous materials consisting of molecules that are different not only in molecular weight and tacticity, but also in comonomer distribution. The comonomer can alter the stereo regularity of the chain, thus reducing crystallinity. From a stereochemical point of view, the copolymers of propylene by ZN catalysts can be considered as blocks, having isotactic chain segments or isotactic blocks that are interrupted by atactic chain segments or atactic chain blocks. Driven by thermodynamic forces, the isotatic blocks will aggregate to form crystals that have essentially the same melting point as homopolypropylene. In terms of crystalline structure, propylene copolymers are basically those of iPPs but have a lower crystallinity.

The Z-N type of propylene homopolymers and copolymers has not found use in adhesive application due to its high melting point and high crystallinity. The melting point of polypropylene crystals is typically around 165-170 ° C. This implies that the hot melt adhesives that contain them will remain solid until the polypropylene's melting point of approximately 170 ° C is reached, at which point the hot melt begins to melt and become liquid. Empirically, the application temperature of a hot melt adhesive is required to be 20-30 ° C higher than the melting point or softening point of the adhesive. Actual application temperature should be at least 200 ° C if conventional PP-based adhesive exists. At this temperature, the hot melt can degrade rapidly, causing various throughput and processing problems.

Single site catalyst systems (SSC) differ from conventional ZN catalysts in at least one significant respect. They have a single active transition metal site for each catalyst molecule, and therefore the activity at this metal site is identical for all catalyst molecules. One type of SSC catalyst that has now been widely used on an industrial scale is a metallocene catalyst system consisting of a catalyst and a cocatalyst or activator. The catalyst is a transition metal complex that has a metal atom located between two cyclic organic ligands; the ligands are the same or different derivatives of cyclopentadiene. The cocatalyst can be any compound capable of activating the metallocene catalyst by converting a metallocene complex into a catalytically active species and an example of such a compound is alumoxane, preferably methylalumoxane, which has an average degree of oligomerization of 4 to 30. For the purpose of this invention, other neutral or ionic activators may be used, including, but not limited to, various organic boron compounds such as tri (n-butyl) ammonium tetrakis-pentafluorophenylborate, dimethylanilinium tetrakispentafluorophenylborate, or trityl tetrakis-pentafluorophenylborate. Another type of SSC catalyst is the constrained geometry catalyst (CGC).

As used herein, CGC refers to a subclass of the SSC catalyst system known as a constrained geometry catalyst. Unlike metallocenes, the restricted geometry catalyst (CGC) is characterized by having only one cyclic ligand attached to one of the other ligands in the same metal center in such a way that the angle in this metal between the centroid of the pi system and the additional ligand is smaller than in complexes without comparable bridges. More specifically, the term CGC is used for ansa bridged cyclopentadienylamido complexes, although the definition goes well beyond this class of compounds. Therefore, the term CGC is widely used to refer to other more or less related ligand systems that may or may not be isolobal and / or isoelectronic with the ansa bridged cyclopentadienylamido ligand system. In addition, the term is often used for complexes related to long loop bridges that do not induce stress.

Like the metallocenes, suitable CGCs can be activated methylaluminoxane (MAO), perfluorinated borans, and trityl borate cocatalysts. However, CGC-based catalyst systems show the incorporation of higher alpha-olefins to a much greater extent than comparable metallocene-based systems. Non-metallocene-based SSCs, also called post-metallocene single-site catalysts for olefin polymerization are also known. Typical post-metallocene catalysts have bulky, neutral alpha-diimine ligands. However, these post-metallocene catalysts are most often used for the polymerization of ethylene to produce plastomers and elastomers. They are rarely used for the polymerization of α-olefins such as propylene. Single-site catalyst systems for olefin polymerization are well known to those skilled in the art and are extensively discussed in two symposia titled Stereoselective Polymerization with Single-Site Catalysts edited by Lisa S. Baugh and Jo Ann M. Canich published by CRC press (2008) and Polyolefins: 50 Years after Ziegler and Natta II: Polyolefins by Metallocenes and Other Single-Site Catalysts edited by Walter Kaminsky and published by Springer Heidelberg (2013).

The advancement of the SSC catalyst systems described herein above has made it practical to produce propylene-based polymers and copolymers having various chain microstructures and specific stereochemistry. Depending on the choice of catalyst and reaction conditions, specific types of propylene polymers and copolymers, for example, may have a narrow molecular weight distribution, statistically random comonomer incorporation, high fraction of atactic chain sequences and sequences of shorter crystallizable isotactic or syndiotactic chain. Macroscopically, the polymers exhibit low melting point, low enthalpy of fusion, low crystallinity and low density and behave more similarly to elastomers than to conventional polypropylene. These polymers have several weight average molecular weights (Mw) ranging from 1000 g / mol to 1,000,000 g / mol, having been produced with a melting point between 20 ° C and 150 ° C, which is well below the point melting melt of 170 ° C of iPP, with a melting enthalpy between 0 J / g and 100 J / g and with a density between 0.85 g / cc and 0.90 g / cc. Some of these polymers are well suited for hot melt adhesive applications.

The composition of the present invention advantageously comprises a blend of a semi-crystalline LMW SSC-PP polymer and an essentially amorphous HMW SSC-PP polymer made herein with suitable single site catalysts. The weight ratios of LMW PP polymer to HMW PP polymer in blends range from 9: 1 to 1: 9 and the total amount of polymer blend in the composition of the present invention is from about 20% to about 80%. by weight, preferably from about 30% to about 60% by weight, and most preferably from about 30% to about 50% by weight.

The semi-crystalline LMW SSC-PP polymer (also referred to as a PP-based polymer) in the hot melt adhesive composition of the present invention comprises a homopolymer or a copolymer of propylene with at least one comonomer selected from the group consisting of ethylene and an alpha-olefin. having a carbon chain length of 4 to 8, having from about 70% by weight to about 99% by weight, preferably from about 80% by weight to about 98% by weight, and most preferably from about 85% by weight to about 98% by weight of propylene. The semi-crystalline LMW SSC-PP polymer has a weight average molecular weight of from about 10,000 g / mole to about 100,000 g / mole, preferably from about 10,000 g / mole to about 80,000 g / mole, and most preferably from about 10,000 g / mole. mol to about 60,000 g / mol, a melting point measured using DSC of from about 20 ° C to about 150 ° C, preferably from about 30 ° C to about 110 ° C, and most preferably from about 40 ° C to about 100 ° C, and having a melting enthalpy measured using DSC of about 30 J / g to about 100 J / g, preferably about 35 J / g to about 80 J / g and most preferably about 35 J / g to about 60 J / g . These enthalpies of fusion correspond to a degree of crystallinity, calculated from the enthalpy of fusion using 190 J / g for 100% crystalline isotactic PP, from about 18% to about 53% by weight, preferably from about 18% by weight. to about 42% by weight, and most preferably from about 18% by weight to about 32% by weight. Furthermore, the LMW SSC-PP polymers have a Brookfield viscosity at 190 ° C that preferably ranges from about 800 mPa.s to about 100,000 mPa.s and most preferably from about 1,000 mPa.s to about 20,000 mPa.s. In some embodiments, the semi-crystalline LMW SSC-PP polymer has a weight average molecular weight of from about 10,000 g / mole to about 30,000 g / mole, preferably from about 12,000 g / mole to about 29,000 g / mole and the most preferably from about 15,000 g / mol to about 27,500 g / mol.

The essentially amorphous HMW SSC-PP polymer (also referred to as a PP-based polymer) in the hot melt composition of the present invention is a propylene homopolymer or a propylene-based copolymer with at least one comonomer selected from the group consisting of ethylene and a alpha-olefin having a carbon chain length of 4 to 8, having from about 70% by weight to about 99% by weight, preferably from about 80% by weight to about 98% by weight, and most preferably from about 80% by weight to about 90% by weight of propylene. The HMW SSC-PP polymer has a weight average molecular weight of greater than 100,000 g / mole, preferably from about 100,000 g / mole to about 1,000,000 g / mole, and most preferably from about 100,000 g / mole to about 600,000 g. / mol. Furthermore, the HMW SSC-PP polymer is a predominantly amorphous material with no DSC melting peak or having little residual crystallinity, exhibiting a DSC melting peak of about 20 ° C to about 120 ° C, preferably about 30 ° C to about 100 ° C and most preferably from about 40 ° C to about 80 ° C, and having an enthalpy of fusion measured using DSC of from about 0 J / g to about 30 J / g, preferably from about 5 J / g to about 25 J / g and most preferably about 5 J / g to about 20 J / g. These enthalpies of fusion correspond to a degree of crystallinity, calculated from the enthalpy of fusion using 190 J / g for 100% crystalline isotactic PP, from about 0% to about 18% by weight, preferably from about 2.6% by weight to about 15.8% by weight, and most preferably from about 2.6% by weight to about 13.2% by weight. HMW SSC-PP polymers have a melt index (MFR) according to ASTM D1238 at 230 ° C / 2.16 kg under test conditions of approximately 1 g / 10 min to approximately 200 g / 10 min, preferably approximately 10 g / 10 min to about 60 g / 10 min and most preferably from about 20 g / 10 min to about 100 g / 10 min. Preferably the composition does not contain styrene content.

According to an embodiment of the invention, the molecular weight of the HMW PP polymer is at least twice the molecular weight of the LMW SSC-PP. Preferably, the molecular weight of the HMW PP polymer is at least three times greater than the molecular weight of the LMW SSC-PP. More preferably, the molecular weight of the HMW PP polymer is at least five times greater than the molecular weight of the LMW SSC-PP. The molecular weight of the HMW PP polymer can even be at least eight to ten times greater than the molecular weight of the LMW SSC-PP. By using two polymeric constituents with such molecular weight offsets relative to any adhesive disclosed herein, it has been found that the purposes of the invention can be more easily achieved.

Compatible tackifying resins or tackifiers used in the hot melt adhesives of the present invention are those that extend adhesive properties and improve specific adhesion. As used herein, the term "tackifying resin" includes:

(a) Aliphatic and cycloaliphatic petroleum hydrocarbon resins having ring and ball softening points (R&B) of 10 ° C to 150 ° C, as determined by the ASTM E28-58T procedure, subsequent resins resulting from polymerization of monomers consisting mainly of aliphatic and / or cycloaliphatic olefins and diolefins; Also included are hydrogenated aliphatic and cycloaliphatic petroleum hydrocarbon resins; Examples of such commercially available resins based on such a C5 olefin fraction are Piccotac 95 tackifying resin available from Eastman Chemicals and Escorez 1310LC available from ExxonMobil Chemical Company and examples of cyclopentadiene-based hydrogenated cycloaliphatic petroleum hydrocarbon resins are Escorez 5400 from Exxonmobil and Resinall R1095S from Resinall Corporation;

(b) aromatic petroleum hydrocarbon resins and their hydrogenated derivatives; an example of a hydrogenated aromatic hydrocarbon resin is Arkon P-115 from Arakawa Chemicals;

(c) aliphatic / aromatic petroleum derived hydrocarbon resins and their hydrogenated derivatives;

(d) aromatic modified cycloaliphatic resins and their hydrogenated derivatives;

(e) polyterpene resins that have a softening point of about 10 ° C to about 140 ° C, these latter polyterpene resins generally result from the polymerization of terpenic hydrocarbons, such as the mono-terpene known as pinene, in the presence of catalysts Friedel-Crafts at moderately low temperatures; hydrogenated polyterpene resins are also included;

(f) copolymers and terpolymers of natural terpenes, for example styrene / terpene, α-ethylstyrene / terpene and vinyl toluene / terpene;

(g) natural and modified rosin such as gum rosin, wood rosin, tall oil rosin, distilled rosin, hydrogenated rosin, dimerized rosin and polymerized rosin;

(h) Glycerol and pentaerythritol esters of natural and modified rosin, such as, for example, glycerol ester of light wood rosin, glycerol ester of hydrogenated rosin, glycerol ester of polymerized rosin, ester of pentaerythritol light wood rosin, hydrogenated rosin pentaerythritol ester, tall oil rosin pentaerythritol ester and phenolic modified pentaerythritol rosin ester; Y

(i) Phenolic-modified terpenic resins, such as, for example, the resin product resulting from the condensation in an acidic medium of a terpene and a phenol.

Mixtures of two or more of the tackifying resins described above may be necessary for some formulations. Although a range of from about 15% to about 75% by weight of tackifying resin can be used, the preferred amount is from about 30% to about 60% by weight. Tackifier resins that are useful for the present invention may include polar tackifier resins. However, the choice of available polar tackifying resins is limited in view of the fact that many of the polar resins appear only partially compatible with polyolefins.

As indicated above, tackifying resins that are useful within the scope of the present invention comprise from about 15% to about 75% by weight, preferably from about 30% to about 60% by weight, of the composition. . Preferably, the tackifying resins can be selected from any of the non-polar types that are commercially available. Preferred resins are aliphatic petroleum hydrocarbon resins and most preferred are non-polar products such as hydrogenated dicyclopentadiene (HDCPD) or aromatically modified derivatives thereof with softening points above 70 ° C. Examples of such resins are Escorez 5400 and Escorez 5600 sold by ExxonMobil Chemical Company.

A plasticizer may be present in the composition of the present invention in amounts from about 1% to about 35% by weight, preferably from about 2% to about 20% by weight, in order to provide the desired viscosity control and provide flexibility. . A suitable plasticizer can be selected from the group including the usual plasticizing oils, such as mineral oil, but also olefin oligomers and low molecular weight polymers, as well as vegetable and animal oils and derivatives thereof. The petroleum-derived oils that can be used are relatively high-boiling materials containing only a minor proportion of aromatic hydrocarbons. In this regard, the aromatic hydrocarbons should preferably be less than 30% and more particularly less than 15% of the oil, measured by the fraction of aromatic carbon atoms. More preferably, the oil can be essentially non-aromatic. The oligomers can be polypropylenes, polybutenes, hydrogenated polyisoprenes, hydrogenated polybutadienes, or the like having an average molecular weight between about 350 g / mole and about 10,000 g / mole. Suitable vegetable and animal oils include glycerol esters of common fatty acids and polymerization products thereof. Other useful plasticizers can be found in the families of conventional dibenzoate, phosphate, phthalate esters, as well as mono- or polyglycol esters. Examples of such plasticizers include, but are not limited to, dipropylene glycol dibenzoate, pentaerythritol tetrabenzoate, 2-ethylhexyldiphenyl phosphate, di-2-ethyl polyethylene glycol 400-hexoate; butylbenzyl phthalate, dibutyl phthalate and dioctyl phthalate. The plasticizers that find utility in the present invention can be any number of different plasticizers, but the inventors have found that mineral oil and liquid polybutenes having an average molecular weight of less than 5,000 g / mol are particularly advantageous. As will be appreciated, plasticizers have typically been used to reduce the viscosity of the overall adhesive composition without substantially lowering the adhesive strength and / or service temperature of the adhesive, as well as to extend the open time and improve the flexibility of the adhesive.

Waxes can be used to reduce the viscosity of the hot melt adhesive composition. Although amounts ranging from about 0% to about 20% by weight can be used in the composition of the present invention, preferred amounts are between about 0.1% to about 15% by weight, if used. In one embodiment, no wax is included in the adhesive composition. These waxes can also affect make-up time and the softening point of the adhesive. Useful waxes include:

1. low molecular weight, that is, number average molecular weight (Mn) equal to 500-6000 g / mol, polyethylene having a hardness value, as determined by the ASTM D-1321 procedure, of approximately 0.1 to 120, which has an ASTM softening point of about 65 ° C to 140 ° C;

2. petroleum waxes such as paraffin wax having a melting point of approximately 50 ° C to 80 ° C and microcrystalline wax having a melting point of approximately 55 ° C to 100 ° C, the latter melting points being determined by ASTM D127-60 procedure;

3. synthetic waxes made by polymerizing carbon monoxide and hydrogen such as Fischer-Tropsch wax; Y

4. polyolefin waxes. As used herein, the term "polyolefin wax" refers to those polymeric or long chain entities that comprise olefinic monomer units. These types of materials are commercially available from Westlake Chemical Corporation, Houston, TX under the trade name designation "Epolene" and from Honeywell Corporation, Morristown, NJ under the trade name designation "A-C". Materials that are preferred for use in the composition of the present invention have a ring and ball softening point of from about 100 ° C to 170 ° C. As should be understood, each of these wax diluents is solid at room temperature.

Other substances including hydrogenated animal, fish and vegetable fats and oils such as hydrogenated tallow, lard, soybean oil, cottonseed oil, castor oil, menhadin oil, cod liver oil and the like, and which are solid at room temperature by virtue of being hydrogenated, are also useful in regards to function as an equivalent of wax thinner. These hydrogenated materials are often referred to in the adhesive industry as "animal or vegetable waxes".

The present invention may include a stabilizer in an amount of from about 0.1% to about 3% by weight. Preferably, about 0.2% to 1% of a stabilizer is incorporated into the composition. Stabilizers that are useful in the hot melt adhesive compositions of the present invention are incorporated to help protect the aforementioned polymers, and thus the entire adhesive system, from the effects of thermal and oxidative degradation that normally occur during manufacture and adhesive application, as well as in the ordinary exposure of the final product to the environment. Applicable stabilizers include high molecular weight hindered phenols and multifunctional phenols, such as sulfur and phosphorous containing phenols. Hindered phenols are well known to those skilled in the art and can be characterized as phenolic compounds that also contain sterically bulky radicals in the vicinity of the phenolic hydroxyl group thereof. In particular, tertiary butyl groups are generally substituted on the benzene ring in at least one of the ortho positions relative to the phenolic hydroxyl group. The presence of these bulky sterically substituted radicals in the vicinity of the hydroxyl group serves to retard their stretching frequency and, consequently, their reactivity; This steric hindrance thus provides the phenolic compound with its stabilizing properties. Representative hindered phenols include:

1,3,5-trimethyl-2,4,6-tris (3-5-di-tert-butyl-4-hydroxybenzyl) benzene;

pentaerythirtol tetrakis-3 (3,5-di-tert-butyl-4-hydroxyphenyl) propionate;

n-octadecyl-3 (3,5-di-tert-butyl-4-hydroxyphenyl) propionate;

4,4'-methylenebis (4-methyl-6-tert-butylphenol);

2,6-di-tert-butylphenol;

6- (4-hydroxyphenoxy) -2,4-bis (n-octylthio) -1,3,5-triazine;

2,3,6-tris (4-hydroxy-3,5-di-tert-butyl-phenoxy) -1,3,5-triazine;

di-n-octadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate;

2- (n-octylthio) ethyl-3,5-di-tert-butyl-4-hydroxybenzoate; Y

sorbitol hexa-3 (3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

The performance of these stabilizers can be further improved by using, in conjunction with them,; (1) synergists such as, for example, thiodipropionate esters and phosphites; and (2) chelating agents and metal deactivators such as, for example, ethylenediaminetetraacetic acid, slats thereof, and disalicylalpropylene diimine.

It should be understood that other optional additives may be incorporated into the adhesive composition of the present invention to modify particular physical properties. These can include, for example, materials such as inert colorants, for example titanium dioxide, fillers, fluorescent agents, UV absorbers, surfactants, other types of polymers, etc. Typical fillers include talc, calcium carbonate, clay silica, mica, wollastonite, feldspar, aluminum silicate, alumina, hydrated alumina, glass microspheres, ceramic microspheres, thermoplastic microspheres, barite, and wood flour. Surfactants are particularly important in hygienic disposable nonwovens because they can dramatically reduce the surface tension, for example, of the adhesive applied to the diaper core, allowing for faster transport and subsequent absorption of urine by the core.

The hot melt composition of the present invention is further characterized by having a low viscosity measured by ASTM-D3236 using a Brookfield viscometer at 177 ° C ranging from 500 mPa.s to approximately 35,000 mPa.s, preferably from approximately 1,000 mPa.s to approximately 20,000 mPa.s and more preferably from about 2,000 mPa.s to about 15,000 mPa.s. Certain embodiments are essentially amorphous with no melting peaks or small on a DSC curve spanning a temperature range of -60 ° C to 160 ° C. DSC curves are obtained using a TA Instrument Q1000 DSC and the test procedure described herein below. Other embodiments are semi-crystalline ones that have a notable melting peak on a DSC curve in the same temperature range. In addition, the composition has an R&B softening point of from about 60 ° C to about 120 ° C, most preferably from about 80 ° C to about 110 ° C, according to ASTM E-28 test procedures using glycerol as the medium with an automated Herzog tester, a density from about 0.85 g / cc to about 1.00 g / cc at 20 ° C per ASTM D792-13.

The hot melt adhesive composition of the present invention can be formulated using any of the techniques known in the art. A representative example of the prior art mixing procedure involves placing all of the components, except the polymers used in the present invention, in a jacketed mixing kettle equipped with a rotor, and then raising the temperature of the mixture to a range of 150 ° C to 200 ° C to melt the contents. It should be understood that the precise temperature to be used in this step will depend on the melting points of the particular ingredients. First, the semi-crystalline LMW PP polymer and then the essentially amorphous HMW PP polymer are subsequently introduced into the kettle with stirring and mixing is allowed to continue until a consistent and uniform mixture is formed. The contents of the boiler are protected with inert gas such as carbon dioxide or nitrogen throughout the mixing process. Without violating the spirit of the present invention, various additions and variations can be made to the process of the present invention to produce the hot melt composition, such as, for example, applying a vacuum to facilitate removal of trapped air. Other equipment useful for formulating the composition of the present invention includes, but is not limited to, single or twin screw extruders or other variations of extrusion machinery, kneaders, intensive mixers, Ross ™ mixers, and the like.

The adhesive composition of the present invention can be used as a general purpose hot melt adhesive in a number of applications such as, for example, disposable nonwoven sanitary articles, paper converting, flexible packaging, woodworking, box sealing and cartons, labeling and other assembly applications. Particularly preferred applications include non-woven disposable diaper and feminine sanitary napkin composition, adult brief incontinence stretch accessory and diaper, diaper core stabilization and pad, diaper backsheet lamination, industrial filter material conversion, gown surgical and surgical drape assembly, etc.

The resulting hot melt adhesives can then be applied to substrates using a varied application technique. Examples include hot melt glue gun, hot melt slot die coating, hot melt roll coating, melt blow coating, spiral spray, contact or non-contact wire coatings such as Omega ™, Sure wrap ™, V procedures. -slot ™ and Allegro ™ and the like. In a preferred embodiment, the hot melt adhesive is applied directly to elastic threads using thread coating processes, which are a preferred technique for elastic bonding in the manufacture of adult incontinence articles and diapers. In one example, the hot melt composition of the present invention is coated using an Allegro ™ nozzle to form a continuous adhesive bond line on elastic threads used for elasticized leg cuffs, cuffs, and waistbands in baby diapers, sweatpants, and articles for incontinence in adults. It is not the intention of this invention to provide a complete description of various techniques and details can be found in the literature or on the nozzle manufacturer's websites www.nordson.com or www.itw.com.

In one embodiment of the invention, a method for making a laminate comprises the steps of: (1) applying the hot melt adhesive composition of the invention in a molten state to a primary substrate; and (2) coupling a secondary substrate to the first substrate by contacting the secondary substrate with the adhesive composition. The primary substrate can be an elastic portion of a diaper, such as an elastic yarn used as part of a leg cuff of a diaper. Such elastic yarns (or bands) and their application as part of a diaper leg cuff are shown in US Patent No. 5,190,606. The secondary substrate may comprise a nonwoven material or a film, such as a spun / melt blown / spun (SMS) nonwoven fabric or a polyethylene film, and the method may include folding the secondary substrate around the elastic yarn. In this way, only the secondary substrate can serve as the substrate that encapsulates the threads of the leg cuff. In an alternative embodiment, a tertiary substrate is used, and the secondary and tertiary substrates can be coupled to the elastic cord on opposite sides of the elastic cord. In such an embodiment, the secondary substrate can be a polyethylene film and the tertiary substrate can be a nonwoven film, or vice versa. Furthermore, a composite diaper backsheet consisting of a polyolefin film bonded to a non-woven fabric can also be used as the aforementioned secondary and tertiary substrates.

In alternative embodiments of the invention, the adhesive is applied to the primary substrate using a hot melt application direct contact method, such as a V-slot or V-groove applicator head. Alternatively, the adhesive can be applied to the primary substrate using a non-contact hot melt procedure, such as a spray applicator. The primary substrate, to which the hot melt adhesive is applied, can be an elastic yarn or a non-woven fabric. In embodiments where the primary substrate is an elastic yarn, the secondary substrate can be a nonwoven fabric wrapped around the elastic yarn, or the secondary substrate could alternatively be elastic between two layers of nonwoven. In such embodiments, the laminate made by the method can be used as an elastic leg cuff, a leg cuff, or an elastic side panel on a disposable article, such as a diaper. In such embodiments, a tertiary substrate can be used, such as a nonwoven fabric. Such a tertiary substrate can also have adhesive applied by direct or non-contact procedures. The laminate of such embodiments can be used as an elastic side panel or a stretched ear on a disposable article.

In other embodiments where the primary substrate is an elastic yarn, the secondary substrate can be a polyethylene film and the tertiary substrate, such as a nonwoven fabric, can adhere to the film. In embodiments where the primary substrate is a nonwoven fabric, the secondary substrate can be an elastic film. As shown in the examples below, the compositions of the present invention give results outstanding, when applied to elastic yarn, in creep tests that simulate performance requirements in industry.

Examples

Brookfield viscosity is tested according to ASTM D-3236 procedure at 325 ° F (163 ° C).

Ring and ball softening point is determined in glycerol with an automated Herzog unit according to ASTM E-28 procedure.

Solid density is measured according to ASTM D792-13 at 23 ° C.

The Differential Scanning Calorimetry (DSC) test is run with a heat-cool-heat program on a TA Instrument DSC Model Q1000. Preferably, a sample of about 10 mg in size is sealed in an aluminum DSC sample tray. The tray is placed in the sample chamber of the instrument and heated at a heating rate of 20 ° C / min from room temperature to 200 ° C, from where the sample is rapidly cooled to -110 ° C. The temperature is raised to 200 ° C at a heating rate of 20 ° C / min and the data is collected. The enthalpy of fusion (AH) measured in joules per gram (J / g) is calculated from the area of the melting peak on the DSC curve using the application software package installed in the Model Q1000 DSC. For the purpose of the present invention, the melting point is defined as the temperature corresponding to the maximum melting peak, that is, the highest point at the melting peak.

Samples for creep testing are prepared using a custom coater / laminator equipped with a Nordson ™ zero cavity hot melt coating module that is designed to accommodate Surewrap ™, Allegro ™, and slotted die tips. For the present invention, an Allegro ™ tip is used to apply the present composition directly to Investa ™ elastic yarns having a fineness of 680 Decitex (dtex). The tip has three separate adhesive nozzles or holes 5mm apart capable of coating three elastic threads simultaneously.

As used herein, decitex (abbreviated dtex) refers to the mass in grams per 10,000 meters of fiber length. It is a measure of the fineness of the fiber in the textile industry.

The shear adhesion test is measured in an incubator at 37.8 ° C (100 ° F) by a modified ASTM D6463 procedure. Specifically, the test specimen used is prepared using a laminate of the present hot melt adhesive between a pair of identical SMS nonwoven webs, the preparation of which is fully described in Examples 1-5 below. The laminate is cut crosswise into a one-inch wide strip to form the test specimen. Before testing, the samples were conditioned in the environment for approximately 12 to 24 hours to ensure the reproducibility and precision of the data. The average value of shear adhesion of three replicates, reported in minutes, is defined as shear strength.

The creep resistance test was performed with rolled samples as described in Examples 1-5. The laminated samples comprise an elastic yarn and non-elastic substrates. A segment of the laminated sample of about 350mm is fully stretched and securely attached to a piece of rigid Polyglass board. A length of 300mm is marked and the elastic threads are cut at the marks while the non-elastic substrates are kept in the stretched configuration. The sample is then placed in a circulating air oven at 100 ° F (37.8 ° C). Under these conditions, elastic yarns under stretch can retract a certain distance. The distance between the ends of the elastic threads is measured after four hours. The ratio between the final length and the initial length, defined as creep retention and expressed as a percentage (%), is a measure of the adhesive's ability to retain the elastic threads.

Vistamaxx 6202, obtained from Exxonmobil Chemical Company, Houston, TX, is an essentially amorphous HMW SSC-PP copolymer containing approximately 15% by weight ethylene comonomer and has a weight average molecular weight (Mw) of approximately 144,700 g / mol, a DSC melting point of approximately 101 ° C, a DSC melting enthalpy of approximately 11.4 J / g, a density of approximately 0.863 g / cc at 23 ° C by ASTM D1505, and a flow rate in melt state (MFR) of about 9.1g / 10min per ASTM D1238 at 230 ° C / 2.16kg test conditions.

Vistamaxx 6502, obtained from Exxonmobil Chemical Company, Houston, TX, is an essentially amorphous HMW SSC-PP copolymer containing approximately 13% by weight ethylene comonomer and has a weight average molecular weight (Mw) of approximately 119,000 g / mol, a DSC melting point of approximately 64 ° C, a DSC melting enthalpy of approximately 9 J / g, a density of approximately 0.865 g / cc at 23 ° C by ASTM D1505, and a melt flow rate (MFR) of approximately 48g / 10min per ASTM D1238 at 230 ° C / 2.16 kg of test conditions.

Vistamaxx 8880, also obtained from Exxonmobil Chemical Company, is a semi-crystalline LMW SSC-PP copolymer consisting of approximately 5.2 wt% ethylene comonomer and has a weight average molecular weight (Mw) of approximately 27,000 g / mol , a DSC melting point of about 96 ° C, a DSC enthalpy of fusion of approximately 38 J / g, a density of approximately 0.880 g / cc at 20 ° C by ASTM D1505 and a Brookfield viscosity of approximately 1,200 mPa.s by ASTM D3236 at 190 ° C.

Licocene 1602, purchased from Clariant, Holden, MA, is an essentially amorphous LMW SSC-PP copolymer consisting of approximately 10% by weight ethylene comonomer and has a weight average molecular weight (Mw) of approximately 20,900 g / mol. , a DSC melting point of 66 ° C, a DSC melting enthalpy of 20.2 J / g, a density of approximately 0.870 g / cc at 23 ° C according to the ISO1183 test procedure, and a Brookfield viscosity of approximately 5,000-7,000 mPa.s according to DIN53019 test procedure at 170 ° C.

Polypropylene LX5 02-15, obtained from Total Petrochemicals USA, Inc., Houston, TX, is a semi-crystalline HMW SSC-PP copolymer containing approximately 2% by weight of ethylene comonomer and has a weight average molecular weight (Mw) of approximately 150,000 g / mol, a DSC melting point of 119 ° C, a DSC enthalpy of fusion of approximately 60 J / g, a density of approximately 0.895 g / cc at 23 ° C by ASTM D1505 and a speed of melt flow (MFR) of approximately 12g / 10min according to ASTM D1238 at 230 ° C / 2.16 kg test conditions.

Escorez 5415, purchased from ExxonMobil, is a very light colored hydrogenated cycloaliphatic hydrocarbon tackifier having an R&B softening point of approximately 115 ° C.

Resinall R1095S is a hydrogenated cycloaliphatic hydrocarbon resin having an R&B softening point of approximately 100 ° C. It is acquired from Resinall Corporation in Severn, NC.

Arkon P-125 is a hydrogenated C9 hydrocarbon resin having an R&B softening point of approximately 125 ° C. Purchased from Arakawa (USA) Inc, Chicago, IL.

Nyflex 222B is a mineral oil plasticizer purchased from Nynas USA Inc., Houston, TX.

AC-596P is a maleic anhydride modified PE wax having a viscosity of approximately 150 mPa s at 190 ° C, a density of 0.93 g / cc, and a dropping point of 141 ° C. It is acquired from Honeywell Corporation, Morristown, NJ.

Clopay DH284 PE is a 20 gram basis weight per square meter (gms) LDPE film purchased from Clopay Plastic Product Co., Inc., Mason, Ohio.

SQN SB15 gsm is a spunbonded nonwoven fabric purchased from First Quality Nonwovens Inc., McElhattan, PA.

Kaydol Oil is a white mineral oil purchased from Sonneborn Inc., Parsippany, NJ.

Eastotack H100L is a partially hydrogenated C5 resin having an R&B softening point of approximately 100 ° C purchased from Eastman Chemical Company, Kingsport, TN.

Irganox 1010 is a hindered phenolic antioxidant purchased from BASF Corporation, Florham, NJ.

The invention is further illustrated by the examples set forth below.

Examples 1-5

The hot melt adhesives of Examples 1-5 shown in weight percent in Table 1 are prepared with the ingredients and mixing procedures described hereinbefore. A total of 2500 grams of each are made and mixing is carried out at 177 ° C under a nitrogen atmosphere in a laboratory-type mixer consisting of a propeller driven by a motor, a heating blanket, a control unit of temperature and a container about 1 gallon in size. The appropriate amounts of each component, calculated according to the proportions shown in the table, except the SSC-PP polymers, are added to the container. The temperature of the container is raised to melt the contents. Once the ingredients in the bowl are completely melted, the motor starts to begin stirring. The semi-crystalline LMW SSC-PP polymer component is then introduced, followed by the essentially amorphous HMW SSC-PP polymer. Mixing is allowed to continue until the polymers are completely dissolved and a uniform mixture is formed. Adhesive Examples 1-5 exhibit high cohesive strength, excellent creep resistance, have a suitable viscosity for processing and application on a range of substrates, and are especially useful for a number of nonwoven hygiene item applications where high creep retention and high shear are needed, including, but not limited to, elastic fitting, meeting zone fitting, stretch panel fitting, clamping fitting, and the like.

Table 1. Examples 1-5

Brookfield viscosity, R&B softening point, density, melting point, enthalpy of melt, shear adhesion, and creep retention tests are carried out in Examples 1 to 5 in accordance with the test procedures described hereinbefore. document. Room temperature tack is judged by the adhesion of the adhesive to human fingers. Specimens for the creep retention test are prepared using the Allegro ™ single wire coating technique on a custom hot melt coater that is equipped with a Nordson Zero Cavity coating module equipped with an Allegro ™ nozzle. Three elastic yarns (Investa 680) are coated, stretched to 300% elongation, each individually from about 148 ° C to about 163 ° C coating temperature. In these coating tests, the angle of entry of the elastic wire into the nozzle guide (that is, the angle between a line normal to the applicator axis and the elastic wire extending between the nozzle and the nearest guide or roller to the nozzle on the inlet side) was kept between 2 and 5 °. The angle of the applicator to the plane of the thread at the outlet was approximately 87 °. (Note that the parameters described above are described using the conventions employed by the nozzle manufacturer in the “Universal Allegro Elastic Coating Nozzles Customer Product Manual, Part 1120705_01” published 2/15). Furthermore, the angle defined by a line normal to the applicator axis and the elastic thread extending between the nozzle and the guide or roller closest to the nozzle on the outlet side was approximately 3 °. Therefore, the applicator was in its standard position, vertically aligned. The adhesives are applied at a speed of approximately 300 meters / minute, 35 milligrams per thread per meter (mg / s / m) of complement, 0.25 second open time, and 40 psi compression on the pressure rollers. The coated yarns are then laminated between a polyethylene film (Clopay DH284 PE) and a spunbonded nonwoven fabric of polypropylene (SQN SB15) to form an elastic laminate.

Samples for the shear adhesion test are prepared on a Model LH-1 tabletop coater equipped with a one-inch die die. The adhesives are coated onto a first SMS nonwoven web at 300 ° F, 50 grams per square meter (gsm) of complement. The first coated SMS web is then laminated to the same second SMS web with 0.25 second open time such that the resulting laminate has a bonded width of one inch and an unbonded width of one inch on each side. The laminate is conditioned for 12-24 hours under ambient conditions before performing a shear test.

Comparative Example 6-9:

Comparative Examples 6-9 are formulated similarly with the components listed in Table 2 using the same procedure as described earlier herein. Unlike Examples 1-5, Examples 6-9 contain a single SSC-PP polymer or with a blend having two essentially amorphous LMW SSC-PP polymers, as opposed to the essentially amorphous HMW SSC-PP polymers of the Examples 1-5. The EJ-6 uses an essentially amorphous Licocene 1602 polymer, but LMW SSC-PP with a residual enthalpy of melting of about 20 g / J. The EJ-7 is formulated with a polymer blend consisting of the semicrystalline Vistamaxx 8880 LMW polymer SSC-PP and the essentially amorphous Licocene 1602 LMW SSC-PP. The EJ-8 contains only Vistamaxx 8880 and EJ-9, Vistamaxx 6502 Viscosity, softening point, density, melting point, enthalpy of melt, and creep retention are obtained using the same test procedures as described herein for Examples 1-5. It is evident that Examples 6-9 exhibit poor creep retention as demonstrated in EJ-6 and 7, or delamination as shown in EJ-8, or too high a viscosity to be coated (Example 9). They lack the balanced properties of Examples 1-5.

Table 2. Comparative Example 6-9

Example-10

The adhesive in Example 10 is prepared using the same procedure described above and ingredients consisting of 45.0% by weight of Vistamaxx 8880, 10.0% by weight of Vistamaxx 6502, 5.0% by weight of Nyflex 222B mineral oil , 29.5% by weight of Escorez 5400 tackifier and 0.5% by weight of antioxidant. The adhesive sample has a Brookfield viscosity of 3,310 mPa.s at 177 ° C (350 ° F) and a softening point of 108 ° C. It is characterized by low viscosity, therefore low application temperature, and excellent resistance to bonding at room temperature and low temperature to varnished / printed or coated cardboard and is particularly useful for carton and carton sealing applications. Samples for bond strength testing are prepared using 4-inch x 1-inch printed cardboard strips as the substrate. The adhesive of Example 10 is applied using a handheld Mini-Squirt ™ glue gun in the form of a bead of approximately 3mm diameter on the printed side of a first substrate strip, and a second substrate strip is immediately applied. in contact and pressed against the first. The room temperature bond strength test is performed by manual peeling after approximately four hours of conditioning to ambient conditions. The low temperature bond strength test is similarly performed at about -25 ° C in a freezer. Three replicates are tested for each temperature and all samples exhibit resistance to fiber breakage, both at room temperature and at low temperature.

Comparative Examples 11 and 12

Two comparative examples were tested which consisted of a polymer blend having a semi-crystalline HMW SSC-PP in combination with an essentially amorphous LMW SSC-PP. This blend is the opposite of the patent application compositions, in which HMW's SSC-PP is essentially amorphous and LMW's SSC-PP polymer is semi-crystalline.

The data and results of these experiments are shown below in Table 3. The following previously unidentified materials were used:

Versify 3000, obtained from Dow Chemical Company, Midland, MI, is a semi-crystalline HMW SSC-PP copolymer containing approximately 5% by weight ethylene comonomer and has a DSC melting point of approximately 115 ° C, an enthalpy of melting by DSC of about 59 J / g, a density of approximately 0.8888 g / cc at 23 ° C by ASTM D1505, a weight average molecular weight of 227,000 and a melt index (MFR) of approximately 8g / 10min by ASTM D123 8 at 230 ° C / 2.16 kg conditions test.

Sucorez 210 is a hydrogenated cycloaliphatic hydrocarbon resin having an R&B softening point of approximately 110 ° C. Purchased from Kolon USA Inc., Atlanta, GA.

Vistamaxx EXP150, obtained from Exxonmobil Chemical Company, is an essentially amorphous LMW SSC-PP copolymer consisting of approximately 13% by weight of ethylene and having a weight average molecular weight (Mw) of approximately 39,200 g / mol, one point DSC melt of approximately 101 ° C, a DSC melt enthalpy of approximately 16 J / g, a density of approximately 0.870 g / cc at 20 ° C by ASTMD1505 and a Brookfield viscosity of approximately 8000 mPa.s by Exxonmobil at 190 ° C.

Table 3

These comparative examples provided a significantly worse creep index than the compositions of the present invention.

Examples 13-16

Additional examples were prepared having 22% by weight to 28% by weight of the essentially amorphous HMW SSC-PP copolymer, Vistamaxx 6502. The formulations and properties are listed in the table below. All examples show a viscosity well within the acceptable range for processing and excellent creep performance with creep retention greater than 97%.

Table 4

Example 17

The heat stability of Examples 1-5 and 13-16 was also tested according to the procedure described below. A 150 gram sample was transferred to an 8 oz glass bottle. The bottle was then covered with a lid without the paper liner. The bottle was then placed in a circulating air oven at 177 ° C. Then a sample was taken at 24 hour intervals and the viscosity was measured at 162.8 ° C. At the same time, the visual appearance of the sample was also inspected and recorded for the formation of carbon, gel, skin, and phase separation or lack thereof. Viscosity and inspection results at 96 hours are reproduced in the tables below:

Table 5

As can be seen, the compositions of the present invention are thermoset. None of the samples of the present invention had a viscosity that decreased by more than 10% over 96 hours. Furthermore, none of the samples of the present invention showed evidence of carbon, gel, skin, and phase separation.

When a range of values is provided, it is understood that each intermediate value, and any combination or sub combination of intermediate values, between the upper and lower limit of that range and any other declared or intermediate value in that established range, falls within the range of cited values. Furthermore, the invention includes a range of a constituent that is the lower limit of a first range and an upper limit of a second range of that constituent.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs.

Claims (15)

1. A hot melt adhesive composition comprising: (a) a polymer blend containing at least one semi-crystalline LMW SSC-PP polymer and at least one essentially amorphous HMW SSC-PP copolymer; which are homopolypropylene or copolymers of propylene with an α-olefin comonomer prepared using SSC catalysts; the weight ratio of the LMW SSC-PP polymer to the HMW SSC-PP polymer in the blends ranges from 9: 1 to 1: 9 and the total amount of the polymer blend in the composition of the present invention is 20% 80% by weight; showing SSC-PP of 1 Mw a density of 0.86 g / cc to 0.90 g / cc at 23 ° C, a weight average molecular weight of 10,000 g / mol to 100,000 g / mol, a melting point of 20 ° C to 140 ° C, a melting enthalpy of 30 J / g to 100 J / g, a crystallinity of 18% to 50%, a melt flow rate equal to or greater than 80 g / 10 min and a Brookfield viscosity at 190 ° C which ranges preferably from 800 mPa.s to 100,000 mPa.s; and the HMW PP polymer having a density of 0.85 g / cc to 0.88 g / cc at 23 ° C, a weight average molecular weight greater than 100,000 g / mol, with no melting point or a residual melt from 20 ° C to 120 ° C, a melting enthalpy of 0 J / g to 30 J / g, a crystallinity of 0% to 18% and a melt flow rate (FMR) equal to or less than 200 g / 10 minutes; (b) a compatible tackifier in the amount of 15% by weight to 75% by weight; (c) from 1% to 35% by weight of a plasticizer; (d) 0.1% to 3% by weight of a stabilizer or antioxidant; Y (e) optionally from 0% to 20% by weight of a wax. The composition of claim 1, wherein the semi-crystalline LMW SSC-PP polymer is a propylene homopolymer. The composition of claim 1, wherein the semi-crystalline LMW SSC-PP polymer is a copolymer of propylene and at least one a-olefin comonomer having the following molecular structure: R-CH = CH ² where R is a hydrogen H, or an alkyl or aryl radical having 4 to 8 carbon atoms. The composition of claim 3, wherein the α-olefin comonomer is ethylene, or butene-1 or hexene-1. The composition of claim 1, wherein the essentially amorphous HMW SSC-PP polymer is a propylene homopolymer. The composition of claim 1, wherein the essentially amorphous HMW SSC-PP is a copolymer of propylene and at least one a-olefin comonomer having the following molecular structure: R-CH = CH ² where R is a hydrogen H, or an alkyl or aryl radical having 4 to 8 carbon atoms. 7. The composition of claim 6, wherein the α-olefin comonomer is ethylene, butene-1 or hexene-1. 8. The composition of claim 1, wherein the plasticizer is selected from the group consisting of mineral oil and liquid polybutene. 9. The composition of claim 1, wherein the adhesive composition further comprises a wax in an amount of up to 20% by weight. The composition of claim 1, wherein the molecular weight of the HMW PP polymer is at least twice the molecular weight of the LMW SSC-PP. The composition of claim 10, wherein the semi-crystalline LMW SSC-PP polymer is present in an amount of between 5% to 50% by weight and the essentially amorphous HMW SSC-PP polymer is present in an amount between 10% to 30%. 12. A procedure for making a laminate comprising the steps of: applying the hot melt adhesive composition of claim 1 in a molten state to a primary substrate; and coupling a secondary substrate to the first substrate by contacting the secondary substrate with the adhesive composition. The method of claim 12, wherein the primary substrate is an elastic yarn. The method of claim 13, wherein the secondary substrate is a nonwoven fabric wrapped around the elastic yarn. 15. A laminate made by the method of claim 12 used as an elastic leg cuff, conventional leg cuff or elastic side panel in a disposable article.